1. Field of the Invention
The present invention relates to the purification of air and, more particularly, to a cryogenic system, which uses a vortex separator for solidifying contaminants and, therefore, provides an effective means for purifying the air.
2. Description of the Related Art
Air pollution in the urban and industrial areas is a severe problem, due to the exhaust products of the factories and automobiles. Fundamental solutions generally involve formidable expenditures and long term technological development. There is a need for on-site, low cost systems that can purify the air for use in automobiles, homes, offices, hospitals, etc. The current state-of-the-art method for air purification is effected by using filters containing substances such as activated charcoal and a variety of chemicals. The shortcomings of such devices are two-fold: First, they can only remove a limited number of pollutants, and secondly, the process is irreversible, therefore, periodic replacement of the devices is necessary, which contributes to the high cost of this type of system.
Several cryogenic techniques have been proposed in attempts to achieve cost effectiveness. Examples include U.S. Pat. No. 4,718,251, entitled "De-Contaminated Fluid Supply Apparatus and Cryogenic Cooling Systems Using Such Apparatus"; U.S. Pat. No. 3,286,954, entitled "Method and Apparatus for Supporting Life in Outer Space"; U.S. Pat. No. 3,144,317, entitled "Freezing Process for Removal of Carbon Dioxide From Air"; U.S. Pat. No. 3,103,427, entitled "Carbon Dioxide Freezeout System"; U.S. Pat. No. 2,413,752, entitled "Separation of the Constituents of Gaseous Mixtures"; and, U.S. Pat. No. 1,717,540, entitled "Process for Preventing Explosions in Liquid-Air Apparatus".
U.S. Pat. No. 4,337,071, issued to L. C. Yang, entitled "Air Purification System Using Cryogenic Techniques" discloses the use of a closed-cycle operated cryogenic refrigerator for cooling air to a cryogenic temperature and, therefore, solidifying contaminants. A filter system can then filter out the solidified contaminants from the air. The refrigeration proposed by L. C. Yang consists of a compressor, a Joule-Thompson valve, multi-stage heat exchangers and expanders. The disadvantage of the use of such expanders is that they must operate at very high speeds with resultant mechanical wearout. Such expanders are quite expensive.